When sensors and integrated circuits are immersed in a conductive fluid, unwanted electrical current can flow, disrupting the operation of the device. For example, a pH sensor and circuit are immersed in a conductive fluid (seawater). The device's sidewalls of the sensor are exposed and un-passivated due to the die separation step (sawing for example). Electrical current can then flow from the exposed sidewalls into the sensor's circuit.
Currently available pH sensors use O-rings or epoxy to seal the conductive fluid from the sidewalls. However, pH sensors for use in the ocean at depths much greater than a kilometer have failures. Specifically, the high pressure of the ocean at depth causes the O-rings or epoxy to fail. This type of failure is exacerbated by repeated pressure cycling. The failure of the O-rings or epoxy allows conductive fluid leaks and current flow from the unpassivated exposed sidewall of the device.